1. Field of the Invention
The invention relates to electroactive molecularly imprinted polymers, and methods and devices using the same for the release of chemical or biological agents. More specifically, the invention embodies devices that utilize a molecularly imprinted polymer to release a chemical or biological agent in response to an electrical signal.
2. Description of Related Art
Most traditional medical therapies involve the administration or dosing of drugs at regular intervals, e.g., once daily or more frequently, and not generally in response to changing conditions within a patient. Time release formulations, which include polymer matrices, coated granules, and microcapsules have been developed to help maintain consistent effective plasma levels of a therapeutic agent over time. However, given that disease is generally defined as a disruption in the consistencies of homeostasis, neither traditional medical therapies nor time release formulations are optimally effective.
For the treatment of insulin-dependent diabetes, patients can use a somewhat more targeted treatment approach (also applicable in some other disease treatments) in which they measure their blood glucose levels at various times throughout the day, and administer an appropriate amount of insulin based upon the glucose concentration at that particular sampling time. Such a system is not optimal, however, for at least two reasons; firstly, it depends upon patient compliance, and secondly, it depends upon analyte (glucose) sampling that is periodic rather than continuous.
Modern drug delivery is moving toward the use of “smart” drug delivery devices. These devices monitor the amount of an analyte in the body and deliver an agent in response to a particular level of analyte. “Smart” drug delivery is important in the treatment of a number of diseases, diabetes and asthma being two prime examples. Both diseases are treated with drugs that have a narrow therapeutic range, because an inappropriately high concentration can have serious adverse effects. U.S. Pat. No. 6,314,317 teaches one such “smart” drug, delivery device. That patent teaches an electroactive polymer having an electroactive pore, through which a therapeutic agent (e.g., a drug) may pass. The pore is controlled by a biologically active electron transfer agent (i.e., an analyte). The biologically active electron transfer agent is capable of transferring an electric charge to the electroactive polymer to enable the electroactive pore to open to allow the release of an agent. Thus, that invention is limited to analytes that interact with electroactive agents such as enzymes, and specifically oxidoreductases (e.g., glucose as an analyte and glucose oxidase as the biologically active electron transfer agent), and their respective therapeutic agents (e.g., insulin).
There is a long felt need for small, implantable “smart” drug delivery devices that release a therapeutic agent in response to changing levels of any one or more of a large number of analytes in a biological system. The need has generally still been unmet, and especially so with respect to analytes that do not have associated therewith a specific electroactive agent, such as many neurotransmitters.